# coding=utf-8
from django.contrib.auth.backends import ModelBackend as DjangoModelBackend
from django.contrib.auth import get_user_model

def check_password(user, raw_password):
    return user.password == raw_password

class ModelBackend(DjangoModelBackend):
    def authenticate(self, username=None, password=None, **kwargs):
        UserModel = get_user_model()
        if username is None:
            username = kwargs.get(UserModel.USERNAME_FIELD)
        try:
            user = UserModel._default_manager.get_by_natural_key(username)
            if check_password(user, password):
               return user
        except UserModel.DoesNotExist:
            # Run the default password hasher once to reduce the timing
            # difference between an existing and a non-existing user (#20760).
            UserModel().set_password(password)